<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="jquery-3.7.0.js"></script>
</head>
<body>
<p>Please choose a choice:
<input id="1" type="button" value="UpperCase" >
<input id="2" type="button" value="LowerCase" >
</p>
<script>
$("#1").click(function(){
	$.ajax(function(){
		url: 'convert',
		data: {
			'method': '1',
		}
	})
})
$("#2").click(function(){
	$.ajax(function(){
		url: 'convert',
		data: {
			'method': '2',
		}
	})
})
</script>
</body>
</html>